1. Technical Field
The present invention relates to embedded storage devices, and more particularly, to an embedded storage device with multiple low-capacity storage units integrated by a relay bus.
2. Related Art
Due to ever-changing storage technology and process techniques, debut of new storage devices never ceases, and thus the storage space and access speed of conventional storage devices are increasing rapidly. To cope with each launch of a new storage device process technique, for example, the improvements in NAND flash memory fabrication as evidenced in its change from a 70 nm process to a 50 nm process, then to a 40 nm process, and eventually to a 30 nm process, electronic product manufacturers have to redesign the operating systems of the electronic products in accordance with the updated process techniques so as to adapt to or manage the novel storage devices. In doing so, any forthcoming launch of a new electronic product model has to be postponed to the detriment of product lifecycle management.
In view of this, the MultiMediaCard Association set forth Embedded MultiMediaCard (eMMC) standards. The eMMC standards aim to simplify use of a storage device installed in an electronic product and integrate both the storage device and a processor into a Multi-Chip Package (MCP) chip. Under the eMMC standards, electronic product manufacturers only need to procure eMMC chips for direct use with the electronic products they developed, thereby dispensing with the hassles of solving the intricate problems with new storage chip compatibility and management, and dispensing with the need to redesign any related peripheral circuit. Hence, the eMMC standards effectively improve electronic product manufacturers' product development schedule, cut product development costs, and speed up the launch of new product models.
Under the eMMC standards, a memory cell chip and a control chip are packaged together and thus integrated to form a single chip, thereby resulting in advantages thereof as follows: sparing parts and components, reducing circuit board area requirement, and thus applying to lightweight thin mobile device products, such as smartphones, tablet computers, and notebook computers. Hence, as smartphones and mobile devices are all the rage, the eMMC standards are increasingly eye-catching to manufacturers and thus are widely accepted by the manufacturers nowadays. Accordingly, the eMMC standards have become the mainstream standards of embedded memory, and eMMC4.3 is the latest version.
Under the eMMC standards in use today, not only is it necessary to change the memory cell chip in order to alter eMMC storage capacity, but multiple storage units in an embedded storage device communicate with a processor separately and thus are regarded as different disks at the computer system end.